Tracking Working Group
Report
Mike Ronan
LBNL
ALCPG 2004 Winter Workshop
SLAC, January 7-10, 2004
1
Detector Working Group: Tracking
Tracking Session I
Time
1:00-1:15
1:15-1:30
1:30-1:45
1:45-2:00
2:00-2:20
2:20-2:40
2:40-3:00
Wednesday, Jan. 7, 1:00-3:00
Title
General Introduction
General Thoughts About Tracker Designs
TPC Studies at UVIC
TPC Studies at Carleton
Beam Tests of a GEM-Based TPC
Some Comments on TPC Tracking
GEM Manufacture
Tracking Session II
Speaker
Bruce Schumm
Richard Partridge
Dean Karlen
Kirsten Sachs
Mike Ronan
Hans Bichsel
Ian Shipsey (Dan Peterson)
Wednesday, Jan. 7, 4:00-6:00
Time
Title
Speaker
4:00-4:20
Magnetic Field Tests of a Micromegas TPC
Mike Ronan
4:20-4:30
Tracking R&D at Cornell and Purdue
Dan Peterson
4:30-4:50
Forward Tracking and the Use of GEM's
Lee Sawyer
4:50-5:20
TPC Response Simulation and Pattern Recognition
Dan Peterson
5:20-5:40
Progress & Plans for Bunch Timing w/ Scintillating Fibers
Rick Van Kooten
Thin Silicon Detectors
Daniela Bortoletto
Tracking Session III
Time
8:30-8:20
8:50-9:05
9:05-9:25
9:25-9:45
9:45-10:05
10:05-10:30
Friday, Jan. 9, 8:30-10:30
Title
Gamma-Gamma -> Hadrons Backgrounds
Pattern Recognition Studies at South Carolina
SD Outer Tracker Studies at SLAC
Frequency Scanned Interferometer Demonstration System
Progress Towards a Short-Shaping Time Solid State Tracker
Closing Discussion
Session convenors: Bruce Schumm, Dean Karlen & Keith Riles
Speaker
Tim Barklow
Achim Weidemann
Steve Wagner
Haijun Yang
Bruce Schumm
All
2
North American Large TPC detector simulations
LCD Modules:
Pattern recognition
Event display
3
Reminder: GEM and Micromegas
GEM: Two copper perforated
foils separated by an
insulator
The multiplication takes
place in the holes.
Usually used in 3 stages,
even 4
Micromegas : a micromesh
sustained by 50-100 mm - high
insulating pillars.
The multiplication takes place
between the anode and the
mesh
One stage
200 mm
Slide stolen from P. Colas Amsterdam
Tracking meeting March 31 2003
4
GEM Manufacture, I.Shipsey (D.Peterson)
3M GEM’s
Aging
NITPC Gas
Single roll of
~1,000 GEMS
Chicago, Purdue
Preliminary studies
performance is equivalent
to CERN GEMs, cost
potentially lower
3M Micromegas
Purdue
After 400 hours of irradiation
5.4 keV X-ray peak
5
TPC Studies at U.Victoria, D.Karlen
First MPGD TPC tracking in magnetic fields.
GEM-based TPC
Triple GEM
8 pad rows
2mm X 6 mm
B=0T
Charge spreading
Suppressed by magnetic field
in low field drift region ()
After pre-amplification in
first GEM, make use of large
diffusion in higher field transfer
and induction gaps.
Point resolution
Down to 90 mm compared to
60 mm expected.
resolution (mm)
Cosmic ray tests
TRIUMF 0.9T magnet
DESY 5.3T magnet
B=0.9T
B=2.5T
B=4.5T
B=0
B = 0.9 T
B = 1.5 T
3 cm
drift time (50ns time bins)
30 cm
6
Beam Tests of a GEM-TPC, M. Ronan
GEM-TPC:
gases Ar-CH4
Ar-CO2
Ar-CO2-CH4
Karlsruhe, CERN, LBNL
- TESLA TDR gas
Achieve resolutions of < 100 mm with high
efficiency, meeting TESLA TPC design
requirements.
Drift velocity
measurement
~4.5 cm/msec
at E = 250 V/cm
7
Magnetic Field Tests of a Micromegas TPC, M.Ronan
Berkeley, Orsay & Saclay
Gas
Argon CF4 3%
Diffusion
E field
200 V/cm
v drift
10 cm/msec
diffusion
~400-500 mm
@ 1 cm
Micromegas
Vmesh
340 V
150 mm/cm
Expected transverse diffusion
B field
0T
0.5 T
1T
2T
3T
4T
 Diff.(mm/cm)
0
400
2.5 150
5
80
10
40
15
27
20
20
For B = 3 T and
d = 50 cm 1 m
188
266
0 cm
2.5 m
421 mm
50 cm
==> Can't measure track width at B = 2T in
using Ar-CF4 with present readout system.
8
TPC Studies at Carleton, K.Sachs
X-ray source
X-ray source, colliminated photon
conversion creates electron cloud,
size ~50mm
 TPC test cell, 5mm drift distance,
gas: Ar:CO2 (90:10)
Micromegas signals
 Study both double GEM and
Micromegas
 Use resistive anode to spread
charge
micromegas
Point resolution
70 mm
9
Tracking R&D at Cornell and Purdue, D.Peterson
Cornell:
Electronics Purchase: VME Crate and Interface
Lab funds
FADC, 100 Mhz, 32 channels
HV crate and computer interface
HV supplies: GEMS
20 KV supply module
TPC Construction (Design influenced by Victoria TPC)
60 cm drift
8.75” OD (Min. for mounting a 10cm GEM)
acrylic construction
==> Parts are being machined in LEPP shop.
Brass field cage hoops and acrylic hoop
support bars are completed.
Cornell
TPC Field cage
Purdue
3M GEM aging
Purdue:
Readout module construction waiting for pad
design and drawing of mounting scheme.
Meanwhile, aging tests of 3M GEM’s are continuing.
Now up to 3 mC/mm2
10
TPC Response Simulation and Pattern Recognition, D.Peterson
Cornell
Response simulation
e.g.
Clustering in r-f
criteria for minimum central pad ,
added adjacent pads splitting at a local
minimum, can lead to pulse height merging
and incorrect clustering.
Pattern recognition
Eff.
Segments found in preselected, I.P. pointing,
cones are used as seeds for
finding tracks.
Pad width [mm]
11
Gamma-Gamma -> Hadrons Background, T.Barklow
SLAC
Physics backgrounds
    
     
…
Summary
• Muon pairs and low-pt hadrons
produced in the beam-beam
interaction need to be considered
along with e+e- pairs and high-pt
hadrons.
• Muon pairs and hadrons create
124 detected charged tracks and  ( m b)
510 GeV detected energy per
train. Tracker occupancies
comparable to or greater than the
occupancies from e+e- pairs.
• Further studies required to
determine how well this
background can be tagged and
how much it will interfere with
signal track finding/fitting and
physics analyses.
     
Assume constant
0.3  s  1.5 GeV
    

Ecm (GeV)
12
Yellow = muons
154 m  m 
Red = electrons
Green = charged pions
Dashed Blue = photons with E > 100 MeV
pairs / train
56 GeV / train detected energy
24 detected charged tracks / train
56 hadronic events / train
 
no pt cut; Ecm down to   threshold
454 GeV / train detected energy
100 detected charged tracks / train
13
Bunch Timing with Scintillating Fibers, R. van Kooten
Indiana & Notre Dame
Warm machine
bunch structure
192 1.4 nsec
pulse rate 120 Hz
 background tracks
54 tracks / train
need timing to eliminate bkd tracks
TPC 2.4 nsec
SiD 150 nsec (3 msec, S/N ~ 10)
Track bunch timing
Use scintillating fiber int. tracker
Readout with
VLPC - Visible Light Photon Counter
APD - Avalanche Photodiode
(Geiger mode)
SiPM - Silicon Photon Multiplier
14
Forward Tracking and the Use of GEM's, L.Sawyer
• GEM detector development for
QWEAK tracker.
• Interest in Linear Collider, forward
tracking identified as area needing
work
LA Tech
Computation mesh
– Physics needs include luminosity,
precision electroweak measurements (WW,
WZ),
SUSY searches & measurements (e.g.
selectron production)
• Can a GEM-based detector work in the
Intermediate to Forward region of
proposed LC detector?
– Concentrating on LD, region from lower
TPC to mask (FCH in the TESLA detector
design)
– Competing technologies are straw tubes,
scintillating fibers (intermediate tracker)
15
Thin Silicon Forward Detectors, D.Bortoletto
Purdue
Forward Tracking Detectors
Silicon Outer Tracker
•
•
•
•
•
Issues
Technical problems:
Layout for a forward pixel detector
– Manufacturing of thin devices is difficult
– Thinning after processing is difficult
– Industry has expressed interest in thin silicon
devices
– Collaboration with vendors is critical
Layout for a forward pixel detector
How thin:
– The m.i.p. signal from such a thin, 50µm, silicon
sensor layer is only ~3500 e-h pairs.
R&D at Purdue has started last year. We got quotes from
two vendors: Sintef and Micron
Sintef: min. thickness 140 µm on 4 inch wafers
Micron: 4" Thickness range from 20μm - 2mm, 6"
Thickness range from 100μm - 1mm
16
The SD Tracker
17
SLAC
SD Outer Tracker Studies, S. Wagner
SiD Tracker
Fraction of tracks w/ all correct hits
5 single-sided axial Si layers
7 mm, 3 msec shaping
Project VXD tracks out to SOD.
Simple Helix fit. Assign hits.
Get better as radius increases.
proj. error = 500 mm to 75 mm.
Start with qqbar events with no
background at this time.
1st stage algorithm
80%
Need to show that it’ll work.
 Remaining 20% will be the test!
00
Angle w.r.t. jet axis
18
Short-Shaping Time Solid State Tracker, B.Schumm
RMS
Gaussian Fit
19
Power Off
Power On
60 msec power
restoration
8 msec power-off period (not to scale)
Response to ¼, 1
and 4 mip signals
20
Freq.-Scanned Interferometer Tracker Alignment System, H.Yang
U. Michigan
Basic idea: To measure hundreds of absolute point-to-point distances of tracker
elements in 3 dimensions by using an array of optical beams split from a central laser.
Absolute distances are determined by scanning the laser frequency and counting
interference fringes. Absolute 1D distance accuracy is of order 1 micron.
Demo System
Absolute Distance Measurements
An accuracy of 35 nm, or 50 ppb, was obtained.
21
GEM-TPC Distortion measurements
CERN test beam:
9 GeV hadrons
No problem with GEM operation.
Observe track positive ion distortions at
high intensity.
GEM feedback and TPC
positive ion distortion
models are under study.
22